Now it was to Gerald of Windsor, one of Roger Montgomery's chief followers, that Nest, the beautiful daughter of Rhys ap Tewdwr, was married. This Nest, whose ravishing beauty had won her acclaim as the Helen of Wales, had been a mistress of King Henry I by whom she had a child. Even after her marriage she continued to inflame men's passions and her own cousin, Owain ap Cadwgan, determined to have her as his own. In 1109 with a small band of men, he abducted her from her husband's castle at Cenarth Bychan after tunnelling under the gate. Gerald escaped but the castle was burnt down and Owain and the not unwilling Nest made off to Ireland.

Oral tradition in Cenarth maintained that Nest's castle was located near the village, possibly in the neighbouring woods. The motte itself was taken by the villagers to be a burial mound and tradition had it that it covered the bodies of soldiers killed in abattle long ago. It is interesting to observe that the motte could easily have become a burial place of those killed during the assault on, and destruction of, Nest's castle but tradition is not historical proof and what evidence there is leaves the exact location of Nest's castle unsolved, for medieval documents mention a Cenarth Mawr and a Cenarth Bychan and it is assumed that the Cenarth of today was the Cenarth Mawr of the Middle Ages. Only an archaeological dig at the mound to ascertain whether the castle was actually burnt down can throw more light on the subject.